sin4x+2sin2x/2(cosx+cos3x)=? ;при x=30

Question

sin4x+2sin2x/2(cosx+cos3x)=? ;при x=30

Answer 1

sin4*30+2sin2*30/2(cos30+cos3*30)=

sin120+2sin30(cos30+cos90)=

sin120+2sin1/2(cos корень из3/2+cos0